Login  Register

Re: Case Prep

Posted by Pete v M on Nov 17, 2011; 10:06pm
URL: http://oldforum.flyshooter.com.au/Case-Prep-tp4996793p5002632.html

Well it must be my turn to confuse Deane.
Short range benchrest - 6mmPPC formed from 220 Russian cases. Tight neck chamber and very short free-bore means neck turning is required. After fire-forming to PPC the case is trimmed and chamferred. No other sorting or prep is done.
'F' class std - 223 or 308. Std neck chamber as per the rules for this class. Bullet either jammed in lands or with some short bodied 308 bullets (eg Sierra 155) jumped .050". No case prep - new brass used once only then sold off.  Still hold the record at the local club for 3 ranges with 60, 60, 59.
'F' Open and Fly - as these are always chambers with long free-bore the bullet will self-align if jammed in the lands (see the thread started by Chappo on 'run-out'). I used to uniform the flash-holes with a view to avoiding bent de-capping pins but get lazy sometimes and lately tend to want them as small as possible to try to reduce pressure transmitted to the primer pocket (my loads tend to be hot). Also have found over the years that uniforming primer pockets achieves nothing more than extra work. Brass is never weight sorted but in some instances checked for neck wall uniformity. this is sometimes necessary when the loaded round is too close in size to the neck diameter of the chamber - the cut-off is usually .002" difference from thin side to thick side. Monitoring trim length is important ; mainly from a safety aspect as pressure will go sky-high if the neck bottoms out at the front of the chamber and crimps the neck into the bullet. As our cases are shared across multiple barrels in many calibres full-length sizing is essential. There is another reason for F/L and that has to do with allowing clearance so the bullet can self align. Between firings the cases merely have the necks cleaned before sizing and periodically trimmed and if needed the donut cut out of the neck/shoulder junction. I don't even bother cleaning primer pockets until the build-up of ash is enough to stop the new primer from seating properly. There will be some out there that will think I am bull-shitting but when you have to load over 6,000 rounds per year (remember there are two shooters in this camp and we shoot heaps of matches in various disciplines) you start looking to find what does not NEED doing. Surely the results from over the years in Fly and 1,000yd benchrest speak for themselves. Those who do the full prep should continue as to change could lead to a reduction in confidence.

Pete